This invention is in the field of hospital beds which typically have a lower support frame which may be raised, lowered, or tilted between shock and drainage positions, and an upper frame or mattress support formed of a head section, a thigh section, and a leg section, which are independently tiltable. Thus the head section can be raised to any angle, while the thigh and leg sections remain flat, or vice versa; or the head and thigh sections can be tilted to form a "V", while the thigh and leg sections form an inverted "V". There are obviously a great many possible angles and configurations to satisfy the patient's needs for comfort and medical reasons.
The lower frame may comprise a dolly or carriage on wheels at the bottom, and above it a middle frame which is movable relative to the carriage by known drive means normally operated by cranks extending from the foot-end of the bed or by electric motors. The drive means normally include long drive shafts extending from the crank at the foot-end to a lever below and engaging each of the movable sections of the upper frame. The crank handles are usually designed to pivot relative to the shaft or be totally removable, so as to avoid being an obstacle to persons walking past the foot-end of the bed. Protective side rails extend between the head and foot ends of the bed, these rails being movable in any feasible manner such as pivoting about longitudinal or transverse axes, or even being removable.
The above described hospital beds having provision for various movements and configuration, are generally known in the prior art and may be seen in a variety of publications. They have been described at this time merely to demonstrate the environment in which the present invention is an improvement. These hospital beds are made in great numbers, and at present are relatively complex, quite expensive, and not always reliable to function as intended. Obviously, high cost is a problem in view of present economies; of equal or greater concern is poor reliability, because in actual use there will be little opportunity for correction of malfunction while a patient is in or waiting for the bed.
It is an objective of this invention to provide an improved hospital bed wherein the usual features are retained, additional adjustments may be provided, and the entire mechanism is manufacturable for a substantially reduced cost compared to standard prior art beds. Another consideration in this period is a general policy and desire for conservation of materials and energy, which is attempted by designing the new bed to have fewer parts, to use less material, and to have configurations which produce less scrap or provide uses for the scrap. These objectives have been largely achieved by simplifying parts and mechanisms, and specifically by causing certain single components to serve two, three or more functions. Presented below is a summary of the invention as regards the general concept, followed by a detailed description of the preferred embodiments of this invention.